MINIATURIZED P-V PROBES MAKE POSSIBLE NEW KNOWLEDGE ON OTOACOUSTIC EMISSIONS GENERA- TION MECHANISM AND EAR CANAL INPUT IMPEDANCE.

In this work an innovative methodology for measurement and analysis of Otoacoustic Emissions (OAEs) will be shown. Nowadays noninvasive measurements of OAEs are yielded in the acoustic pressure field only. We realized a device that directly plugs into the human ear canal and can also measure the OAE velocity field. Such a device is equipped with a very small intensity probe com-posed of a micro anemometer MEMS coupled to a sensitive miniature microphone. In this way p-v measurements can be carried out at the same time, providing further information about the mechanisms of OAEs generation, as well as allowing an accurate measurement of input impedance of the ear canal. In this case the p-v measurements of OAEs are best realized on Distortion Product OAEs (DPOAEs), these emissions being more easily measured with our technique. The developed system uses an intensity probe carried out by Microflown and coupled to a dedicated electronic front-end. A high resolution acquisition system is provided by National Instruments and driven by a suitable software developed in LabView platform. This software operates on data recorded in real time and performs a customized analysis of the recorded signals. The results thus obtained, in particular those related to the measurement of the input impedance of the acoustic system, are compared with those already obtained by other indirect methods available in literature.